Question

1.Ram starts working on a job and works on it for 12 days and completes 40% of the work. To help him complete the work, he employs Ravi and together they work for another 12 days and the work gets completed. How much more efficient is Ram than Ravi?
A.50%
B.200%
C.125%
D.100%

Answer 1

Let Ram be able to complete the job in N days.
He works 1/N of the job  per day.  In 12 days, he does  12 / N of the job.
   12/ N = 40/100    =>  N = 30
So Ram does  1/30 th of job each day.

let Ravi work  1/M th of the job each day.  He can finish the job in M days, alone.
The combined working productivity of the two together = 1/30 + 1/ M  per day.
The remaining part of the job after Ram works for 12 days:   100% - 40$ = 60%

   Ram and Ravi complete  60/100 of the job in 12 days
         60/100 = 12 * [ 1/30 + 1/M]
                    = 12/30 +  12 / M
     =>  12 / M = 60/100 - 12/ 30
       =>    1 / M = 5/100 - 1/30  = 1/20 - 1/30 = 1/60
       => Ravi does work in 60 days.  His productivity is 1/60 per day.

productivity of ram -  productivity of ravi = 1/30 - 1/60 = 1/60
     additional efficiency of Ram over Ravi = (1/60) / (1/60)  * 100 = 100%

Ram is twice as productive as Ravi.  So Ram is  100% more efficient as compared to Ravi.